Rolling mill screwdown apparatus



Se t. 24, 1963 M. P. SIEGER ROLLING MILL SCREWDOWN APPARATUS 3 Sheets-Sheet 1 Filed Sept. 19. 1960 NdE Q HIS ATTORNEY Sept. 24, 1963 M. P. SIEGER ROLLING MILL SCREWDOWN APPARATUS 3 Sheets-Sheet 2 Filed Sept. 19, 1960 H I I n o o o o .ww ww m m ZJY F||| Eg M i mvwm MAURICE P, SIEGER BY jdw Q 774%;

HIS ATTORNEY Sept. 24, 1963 Filed Sept. 19, 1960 M. P. SIEGER ROLLING MILL SCREWDOWN APPARATUS 3 Sheets-Sheet 3 SGREWDOWN READJUSTMENT 31,32 LOCKING DEVICE UNIT f $G bN.DRlVE LIMIT HYDRAULIC POSITION WORM xag MOTORS $W|TO\H CYLINDFR TRANSMIII'TE GYLINQER 51 49 62 2s 43 V V LOCKING MAIN DEVICE 67\\OONTROL 69 SERVO Lu 0: D ROLL BALANCE ELECTRO 3 68\ mm. POWER 7| SERVO g um'r VALVE I w 2 g I (I) '53 5 EE scou. DRIVE mm. POWER CONTROL um" I X-RAY 7 GAUGE y A A ELECTRICAL I AMPLg-IER DESIRED ELECTRICAL 74 e UGE 66o CONTROL A CONTROL 4 66b ERROR SIGNAL FIG.6

INVENTOR.

FIG.7

MAURICE P. SIEGER United States Patent 3,104,567 ROLLING MEL SCREWDOWN APPARATUS Maurice P. Sieger, Upper St. Clair Township, Allegheny County, Pa, assignor to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 19, 1960, Ser. No. 56,806 Claims. (Cl. 80-56) This invention relates to an improved screwdown mechanism employed in conjunction with :a rolling mill, utilized for reducing the thickness of material processed thereby, and more particularly to an improved means for rapidly and efliciently rotating the mill screws to adjust vertically one or more of the rolls.

In the usual construction of present day rolling mills, the upper work roll, in the case of a Z-high mill, and the upper work and back-up rolls, in the case of a 4 high mill, are adjustable vertically through a pair of screws to obtain the desired pass, i.e., the opening between the cooperative reducing surfaces of the work rolls, which corresponds to the desired reduced thickness or gauge of the material. The screws are threadably received in individual nuts arranged in the mill housings and are rotatable by individual worm-wheel gear sets to eitect vertical movement thereof. Splines are provided on the upper portions of the screws to permit them to be secured in driving relationship to the gear wheels, but yet allowed to be moved vertically relative thereto.

I In addition to the large horsepower motors, provided to drive the screws, a large numerical speed reduction gearing is usually provided in order to fulfill the large torque requirement necessary to accomplish movement of the screws against the rolling pressures. The aggregate of the operative elements of the screwdown possess combined mechanical and electrical inertia characteristics that limit the adjustment speed of the screwdown when making small adjustments to correct for gauge variations.

In other screwdown arrangements having .a small numerical speed reduction gearing, the mill screws on occasion will become locked against rotation 'by reason of the [frictional forces generated between the respective threads of the mill screws and the nuts. This condition has been found to occur when the rolls are jammed against each other inadvertently or against the material in the instant where the material thickness, unknown to the operator, is substantially greater than the pass opening of the rolls. When this occurs, the screw-down, not having sufficient torque capacity, is unable to tree the screws.

In the interest of obtaining uniformity of strip thickness or gauge from end to end, or as a device for separating the rolls should they become locked, there is a present need to provide a quick, responsive, auixiliary screwdown operating means; wherein the primary screwdown operating assembly will be employed to make a coarse adjustment of the roll-pass opening, while the auxiliary screwdown operating assembly will be employed for 'a Vernier adjustment thereof.

It is the primary object of this invention to provide in a rolling mill a mechanism for adjusting the mill rolls that will be extremely rapid, efiicieut and economical.

It is a particular object of the present invention to provide in a rolling mill an auxiliary screwdown operatiug assembly for rapid roll adjustment that will utilize many of the existing components of the screwdown and necessitate no modification of the housings or of the mill screws.

I It is a still iurther object of this invention to provide means for displacing the worms of the screwdown axially to eiiect a rapid roll adjustment, such means being arranged a considerable distance away from the mill pass ice line and constructed in such a manner that it can be quickly removed and replaced.

It is another object of this invention to provide an automatic locking means operative to permit the mill to be operated as a conventional mill, should the auxiliary screwdown operating assembly for any reason be rendered inoperative.

It is a further object of this invention to provide automatic means for continuously repositioning the auxiliary screwdown operating assembly, after operation thereof to eiiect an adjustment of the rolls, by an adjustment of the primary screwdownoperating assembly without materially disturbing the setting of the rolls, whereby the auxiliary assembly will be always ready to effect :a subsequent roll adjustment.

These objects, as well as the other novel features and advantages of the present invention, become apparent from the following description when read in light of the accompanying drawings of which:

FIG. 1 is a front elevational view of an upper portion of a rolling mill, partly in section to better illustrate certain of the screwdown elements;

FIG. 2 is a front firagmental view partly in section of the worm locking mechanism;

FIG. 3 is a plan sectional view taken on lines 3--3 of FIG. 1, the spur gear case on the left hand side being removed to better illustrate the gearing thereof;

FIG. 4 is an enlarged fragmental sectional elevational view of the worm locking mechanism taken on lines 44 of FIG. 2;

FIG. 5 is a modification of the auxiliary screwdown operating assembly wherein the worms are given both an axial and a rotational movement to elfect rapid roll adjustment;

FIG. 6 is a block diagram of the electrical-hydraulic components that make up the control system :for the primary screwdown operating assembly and auxiliary screwdown operating assembly; and

FIG. 7 is a circuit diagram of the electrical control shown in FIG. 6.

The Primary Screwdown Operating Assembly With reference to FIGS. 1 and 3 there is illustrated the upper portions of the mill housing posts 11 and 12, each provided with windows, not shown, into which there are received the roll assemblies. The mill illustrated is a 4-high mill, although only the upper back-up roll 13 with its lchocks 14 and 15 are shown. The upper rolls of the mill are positioned vertically in the windows and are adjusted to obtain the desired roll opening by operation of vertically arranged mill screws 16 and 17. The screws have threads on their lower ends and splines at their upper ends, the threads being of the same hand and received {by non-rotating nuts 18 and 19 mounted in and secured to the housings l1 and 12.

In order to minimize the friction generated between the screws and the chock-s on the rotation of the mill screws, roller bearings 21 and '22, shown in FIG. 1, are provided which engage the top surfaces of the upper back-up-roll chocks 14 and 1'5 and are supported by the lower ends of screws. As is customary in rolling technology, the checks 14 and 15 are continuously urged upwardly against the screws through the bearings 21 and 22 by a roll balance system of which the chock carrier bar 20- is only shown in the drawings.

The top of each screw, having the spline portions, protrudes through spline apertures provided in horizontally arranged gear wheels 23 and 24 which are rotatably secured to, but prevented from moving vertically in the housings. As shown in FIG. 3, the wheels are driven by individual worms 25 and 26, the worms having elongated splined end portions on which spur gears 27 and 28 are 3 mounted. The gears have corresponding splined apertures, thus'rnaking it possible for the splined ends of the Worms to pass axially therethrough but yet retain driving relationship therewith.

Again, as best shown in FIG. 3, the gears 27 and 28 are received in hearings and held against axial movement thereby. Each gear 27 and 28 is driven by a motor pinion, the pinion 29 being the only one shown in the drawings. The pinions are connected, in turn, to heavy duty motors 31 and 32, the motors being mechanically tied together by a clutch 33. Brakes 34' and 35 are provided for the respective motors 31 and 32.

While the aforesaid elements and the relationships thereof have been modified in certain respects in order to incorporate the features of the present invention, on the whole they are well known in the art. 7

While the worms 25 and 26 could be formed on a common shaft, in the preferred form of the present invention, for convenience of manufacture and assembly, they are made separate and joined together by a bayonet connection as formed on sleeves 37 and 33, the construction being best shown in FIGS. 3 and 4. The sleeves receive roller hearings 39 and 41 provided for the adjacent ends of the worms and serve as extensions for the worms, the sleeves being slidably arranged in the housings so that movement of one sleeve is imparted to the other. The bearings 3-9 and 41 are prevented from moving axially relative to the worms or sleeves and hence axial move! ment of the sleeves will be transmitted to their respective worms.

The Auxiliary Screwdown Operating Assembly The means for displacing the worms in accordance with the present invention consists of a rod 42 which passes through a hole in the worm 26, one end thereof being threadably secured to the sleeve 38 and the other end connected to the piston rod of a double acting piston cylinder assembly 43, sometimes referred to herein as the screwdown cylinder. The cylinder is secured to a frame 44 by bolts, the frame, in turn, being secured to the top of the housing 12. The cylinder assembly employs a hydraulic medium and has the capacity to open or close the pass-opening almost instantaneously on receipt of a signal dictating to it the roll adjustment to be made.

In this construction, on operation of the assembly 43, the rod 42 will impart axial movement to the sleeve 38, which, through the bearing 41, will move the Worm 26 and through the bayonet connection 36, the sleeve 37. Movement of the sleeve 37 is imparted to the Worm 25 through its bearing 39 so that the worms will move axially in unison on operation of the assembly 43 in either direction. Since the threads of the mill screws 16 and 17 are of the same hand, the rotation imparted to the screws on axial movement of the =WOI'II1S 25 and 26 will cause the screws to move vertically in unison thereby to adjust the vertical position of the rolls.

The Automatic Locking Device for the Worms In order to provide for the operation of the mill through the screwdown, i.e., through the motors 3-1 and 32 if for any reason the auxiliary roll adjustment means is rendered inoperative, for example, by failure of the electrical or hydraulic means, or when the cylinder 43 is being replaced, it is a feature of the present invention to provide mean-s for locking the worms against axial movement. In their locked position, however, the worms will operate in their conventional manner. The locking device is best shown in FIGS. 1, 2 and 4 and comprises a rack 45 secured to and arranged at the 'bottom of the sleeves 37 and 38. Directly 'below the rack and slidably received in a box shaped frame 46, which is secured to the housings 11 and 1'2, there is a vertically movable plunger 47 having teeth adapted to mesh with those of the rack. The lower end of the plunger is connected to a toggle comprising a bell crank 48 with one end of the bell crank being connected In one form of employment of the locking device, to

the front of the cylinder 49 there is supplied fluid under a relatively low pressure, say by way of example, from the roll balance system, and, while the rear of the cylinder is connectedto the same pressure source, no fluid is ad mitted to the rear of the cylinder when the plunger is out of engagement with the rack. On failure of the pressure in the screwdown cylinder 43, a locking device control valve 67 will interrupt the fluid being supplied to the front of the cylinder and permit the fluid therein to discharge therefrom. At the same time the valve 67 will permit fluid to be admitted to the rear of the cylinder 49 thereby to raise the plunger 47 and lock the worms 25' and 25 against axial movement. The locking cylinder 49 will also he similarly operated should failure occur of the electrical system employed for the auxiliary roll adjustrnent means. In the event it isdesired'to replace the cylin-,.

der 43, for example, the operator can also cause the locking mechanism to operate.

With reference to FIGS. 1, 3' and 4, there are illus trated the mechanical elements for the mechanism empl-oyed in the present invention for maintaining the piston of the screwdown cylinder 43 in substantially the center of the cylinder. In this way the piston cylinder assembly will always be capable of making a roll adjustment in either direction. Speaking in general terms, this object is accomplished by effecting a rotation of the worms by operating the screwdown through the motors 31 and 32 a degree commensurate with the actual position that the rolls were made to assume on operation of the auxiliary roll adjustment means. At the same time, the auxiliary roll adjustment means will move a similar degree if no gauge correction is being made at that par ticular moment. If a gauge correction is being made at the instant the worms are being moved to reposition the piston of the cylinder 43, then the cylinder will move more or less than the aforesaid degree, depending on whether the material is over gauge or under gauge. In either event, the auxiliary roll adjustment means will 'simultaneously continue to oscillate back and forth to correct for gauge. In order to avoid excessive wear of the screwdown parts, in the preferred embodiment, the, V

screwdown will be operated at predetermined increments, for example, every .020 of an inch of screw travel. To

obtain this coordinating movement through the screw down motors, a rack 55 is secured to one side of the sleeves 37 and 38 arranged on the horizontal center line thereof and engaged by a pinion '56, connected to a verti- The Hydraulic and Electrical System With reference to the diagram shown in FIG. 6 illustrating the electrical and hydraulic components that'go'.

to make up the automatic screwdown control system, blocks are employed to represent the major components. In addition to the reference characters that have been applied to the blocks, legends are used to afford a quick A limit switch 51 is understanding of the control system. The screwdown motors 31 and 32, the locking hydraulic cylinder 49 and its limit switch 51, the worm 26, its position transmitter 62, and the screwdown hydraulic cylinder 43 being shown also in block form.

The screwdown motors 31 and 32 have a control 65 which is connected to a master electrical control unit 66. The hydraulic cylinder 49 of the locking device is connected to the master control 66 through a solenoid locking device control valve 67. The valve 67 is also connected to the roll balance hydraulic power unit 68. The position transmitter 62 is electrically connected to the master control 66, the diagram also indicating mechanical connections between the worm 26, the position transmitter 62 and the screwdown cylinder 43. The screwdown cylinder 43 is connected to the master control 66 through a main modulating type servo valve 69 and an electro-servo valve 71. The pilot of the electro-servo valve is connected to the pilot pressure port of the hydraulic power unit 72. The valve 71 also is a modulating type adapted to open proportionately to the magnitude and direction of the error signal. Thus the valve 71 responds to the signal indicating whether the thickness of the material is over or under gauge. The hydraulic power unit 72 communicates with the main servo valve 69 and supplies the requisite pressure and fluid volume to the screwdown cylinder 43.

The control unit itself is made up of well-known commercial electrical components and as illustrated in FIG. 7 consists of a series of summing points or rheostat networks 66a, 66b, 66c and 66d, arranged in tandem for receiving the electrical signals from the limit switch 51, positioning transmitter 62, locking device control valve 67 and the amplifier and control 74, respectively. A fifth summing point 662 is provided to furnish a signal to the screwdown drive control 65. The control unit also includes a summing amplifier 66 and a power amplifier 66g arranged in series, the latter being electrically connected to the electroservo-valve 71.

The means for measuring the actual thickness of the material being rolled consists of an X-ray gauge 73, al though other types of thickness measuring apparatuses can be employed. The X-ray gauge is connected electrically to the master control 66 through an amplifier and control unit 74, which, in addition to receiving the material thickness signal from the X-ray gauge, also has imposed upon it an electrical signal representing the desired gauge to be obtained. Any'diiference between the actual thickness of the material and the desired thickness will result in an error signal of the proper magnitude and direction being transmitted to the master control 66. The master control, in turn, through the servo valves 69 and 71, will effect a movement of the worm 26 either to the left or right through the screwdown cylinder 43 an amount commensurable with the error signal.

The Modified Form of the Auxiliary Screwdown Operating Assembly In the modification of the roll adjustment apparatus illustrated in FIG. 5, in place of the straight splines provided at the one end of each worm 25 and 26, helical splines 75 are machined on the worm 25 which are received in the recesses formed on the inner surfaces of the sleeves of the spur gears 27 In this construction, it being appreciated that the gear 27 is held a ainst rotation, not only is the worm moved axially on operation of the screwdown cylinder 43, but it is also rotated. This combined action for a given displacement of the worm will have the effect of more quickly rotating the gear wheel 23 than in the arrangement wherein there is only axial movement imparted to the worm.

Operation of the Screwdown t Efiect Gauge Control The following comprises a brief description of the operation of the mechanism in which the control system is employed and the limit switch 51 of the worm locking device closed. The master control will know that the locking cylinder 49 has disengaged the locking plunger 47 and that it is permissible for the worms 25 and 26 to be moved axially. The operator will set the coarse roll pass opened by operating the screwdown motors 31 and 32 in accordance with his rolling schedule. In this action it will be appreciated that the worms will be prevented from moving axially by reason of the resistance set up by the screwdown cylinder 43, it being then in a blocked condition.

When fluid is being admitted to the screwdown cylinder 43 from the hydraulic power unit 72 through the main servo valve 69 and the worms 25 and 26 being free to move axially, the mill screwdown is in readiness for operation by the gauge control apparatus which effects a Vernier adjustment of the rolls. As the leading end of the material passes through the rolls, the X-ray gauge 73 will indicate to the control 74 the actual thickness of the material. An electrical impulse representing the desired gauge has previously been introduced into the control 74 so that any discrepancies between the actual gauge and the desired gauge will result in an error signal of the proper magnitude and direction being transmitted to the master control 66.

This action will result in an electrical gauge correcting signal being sent to the servo valve 71 which Will convert the electrical error signal into an hydraulic error signal and indicate to the main servo valve 69 the proper direction and the amount it should move. Accordingly, the main servo valve 69 will supply to either the front or back of the screwdown cylinder 43 the correct volume of fluid. It is to be appreciated that the electro-hydraulic system provides an almost instantaneous gauge correcting action, the time involved to effect a roll adjustment being only a fraction of a second.

Should the auxiliary screwdown be employed as a means for rapidly separating the rolls in the event the screws become locked, a more simplified control system can be employed without sacrificing the rapid action.

Operation of the Automatic Locking Device for the Worms Should a failure occur in the electrical or hydraulic circuits of the auxiliary roll adjustment apparatus, the locking device control valve 67 will immediately receive a signal from the master control 66 which will automatically effect operation of the locking cylinder 49. In this operation, fluid will be permitted to discharge from the front of the cylinder and at the same time fluid from the roll balance hydraulic power unit 63 will be admitted to the back of the cylinder 49. This will raise the plunger 47 so that its teeth will engage the teeth of the rack 45 and thus prevent axial movement of the Worms 2'5 and 26. The screwdown, however, can thereafter be operated in the conventional manner until the necessary repairs, if any, can be made to the circuit in Which the failure has occurred. Of course, the locking operation can also be effected intentionally by the operator should it be desirable to do so.

Operation of the Repositioning Means for the Auxiliary Screwdown Operating Assembly It is a feature of this invention that the auxiliary screwdown operating assembly be maintained continuously in readiness to make subsequent adjustments of the roll setting either up or down pursuant to the error signal. This repositioning is accomplished by coordinating the operation of the screwdown motors 31 and 32 and the axial movement of the worms 25 and 26. This coordinating effort is brought about through the operation of the position transmitter 62 which is connected to the worms 2'5 and 26 through the rack 55, pinion 56 and mitre gear sets -58 and 61. It is a function of the position transmitter to determine the precise. axial position of the worms .andthe degree of screwdown adjustment the wormsahave eff fected by axial movement thereof. The position transitter :62, being connected to the master control 66 will, as previously mentioned, on adjustment thereof, cause the control 66 to signal the screwdown control 65 to effect operation of the screwdown motors 31 and 32 thereby to rotate the worms to compensate for the distance the Worms are moved axially for centering the piston of the. assembly 43.

It will be appreciated that the primary screwdown operating assembly, in the repositioning operation, will function independently of the auxiliary screwdown operating assembly, so that even as repositioning is eliected, the auxiliary scre-wdown operating assembly will be free to effect a gauge correction.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and. have illustrated and described whatl consider to represent the best embodiment thereof. However, I desire to have it understood that Within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A rolling mill having at leastone pair of cooperative rolls for processing material passed therebetwesn, one of the rolls being movable toward and away from the other by a pair of rotatable screws, a worm and a Worm wheel for rotating each screw, said Worms having their axes in alignment and being interconnected, means for supporting said worms in a manner that they may be rotated as well as moved in an axial direction as a unit, a relatively slou responsive first prime mover for rotating said wormsin unison to effect a simultaneous rotational movement'of said wheels and screws, a relatively fast responsive second prime mover connected to and for axially moving said worms along said support thereby to simultaneously rotate said Wheels and screws independently of the rotational movement imposed thereon by said first prime mover and control means for effecting operation of said second prime mover to efiect a rapid change in the position of said movable roll.

2. A rolling mill according to claim 1 wherein on actuation of said second prime mover said roll will be adjusted a relatively small distance compared with the distance said roll is adjusted on operation of said first prime mover, means interconnecting said first and second prime movers to coordinate morvement thereof whereby on operation of said control means for said second prime mover, said first prime mover will rotate said worms to cause said second prime mover to assume an initial operational position thereby maintaining said second prime mover in readiness for a subsequent operation.

3. A rolling mill according to claim 2 in which said interconnecting means includes a rack secured to at least one of said worms (and movable axially therewith, a pinion in mesh with said rack, and means driven by said pinion for determining the extent of actual movement of 8 said worm, said means connected to said first prime mover to effect operation thereof an-amount commensurate with the axial movement ofsaid worm. i

4. A- rolling mill accordingv to claim 1 wherein said means for axially moving said worm comprises a piston cylinder assembly.

5. A rolling mill according to claim 1 wherein said first prime mover includes a gear speed reducing unit, said worms so connected to said gear unit that they can be simultaneously rotated and moved axially on the respective operations of said first and second prime movers.

6. A rolling rnillaccording to claim 1 including locking means for said worm for preventing axial movement of said worm.

7. A rolling mill according to claim 6 in which said locking means includes a plunger operatively arranged to engage with said worm and means for moving said plunger.

8. A rolling mill according to claim 7 including mean for interconnecting said means for moving said plunger and said means for axially moving said worm whereby in the event said means for axially moving said Worm is rendered inoperative said plunger means will be automatically actuated.

9. A rolling mill according to claim 1 wherein said worm is provided with a series of involute teeth, means for engaging said teeth for effecting rotational movement of said worm as it is axially displaced thereby to increase the degree of rotation imparted to saidwheel for a given axial movement of said Worm.

10. A rolling mill having at least one pair of coopera tive rolls for processing material passed therebetween,

one of the rolls being movable toward and away from the other by a pair of rotatable screws, a worm and aworm wheel for rotating each screw, said worms having their axes in alignment and being interconnected, means for supporting said worms in a manner that they may be ro-' sponsive second prime mover connected to and for axially moving said worms along said support thereby to simultaneously rotate said wheels and screws independently of the rotational movement imposed thereon by said first prime mover, control means for eliecting operationof said second prime mover to effect a rapid change in the position of said movable roll and strip thickness sensing means associated with said control means for eiiecting operation of said control means.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A ROLLING MILL HAVING AT LEAST ONE PAIR OF COOPERATIVE ROLLS FOR PROCESSING MATERIAL PASSED THEREBETWEEN, ONE OF THE ROLLS BEING MOVABLE TOWARD AND AWAY FROM THE OTHER BY A PAIR OF ROTATABLE SCREWS, A WORM AND A WORM WHEEL FOR ROTATING EACH SCREW, SAID WORMS HAVING THEIR AXES IN ALIGNMENT AND BEING INTERCONNECTED, MEANS FOR SUPPORTING SAID WORMS IN A MANNER THAT THEY MAY BE ROTATED AS WELL AS MOVED IN AN AXIAL DIRECTION AS A UNIT, A RELATIVELY SLOW RESPONSIVE FIRST PRIME MOVER FOR ROTATING SAID WORMS IN UNISON TO EFFECT A SIMULTANEOUS ROTATIONAL MOVEMENT OF SAID WHEELS AND SCREWS, A RELATIVELY FAST RESPONSIVE SECOND PRIME MOVER CONNECTED TO AND FOR AXIALLY MOVING SAID WORMS ALONG SAID SUPPORT THEREBY TO SIMULTANEOUSLY ROTATE SAID WHEELS AND SCREWS INDEPENDENTLY OF THE ROTATIONAL MOVEMENT IMPOSED THEREON BY SAID FIRST PRIME MOVER AND CONTROL MEANS FOR EFFECTING OPERATION OF SAID SECOND PRIME MOVER TO EFFECT A RAPID CHANGE IN THE POSITION OF SAID MOVABLE ROLL. 